JPH01286588A - Liquid crystal television receiver - Google Patents

Abstract

PURPOSE:To allow the receiver to cope with various different television systems by using a liquid crystal panel so as to display excellently a signal whose scanning line is 525 and 625. CONSTITUTION:The receiver consists of X drivers 1, 2, a liquid crystal panel 3, Y drivers 4, 5, a timing control circuit 6, a synchronizing separator circuit 7, a 50/60Hz discrimination circuit 8, a vertical counter 9, a vertical direction oscillation drive circuit 10, a horizontal counter 11 and a horizontal oscillation drive circuit 12. Then the liquid crystal panel 3 is nearly subjected to just scanning by a signal of M-NTSC whose scanning line number is 525 and the signal of B/G-PAL or D/K-SECAM or the like whose scanning line number is 625 is displayed by using the same liquid crystal panel 3. When the scanning line number is 625, overscan is applied nearly equally vertically and a picture without unnaturality is displayed. Thus, the signal of various color television system with different scanning line number is received.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is applicable to B/G-PAL, D/Ni-3ECAM, M-N
The present invention relates to a multi-type liquid crystal television receiver that is compatible with various color television systems such as TSC.

(Prior art) In various color television systems such as M-NTSC, B/G-PΔ, and D/8ECAM, parameters such as the number of scanning lines, vertical and horizontal frequencies, etc. as well as color signals are It's different.

Therefore, conventionally, there have been individual system liquid crystal television receivers such as a liquid crystal television receiver 1fi for M-NTSC and a liquid crystal television receiver for B/G-PAL.

To explain an example of an M-NTSC type liquid crystal television screen, its display screen is composed of 220 dots in the vertical direction and 480 dots in the horizontal direction, as shown in FIG.

Since the number of scanning lines in M-NTSC: is 525 and the vertical blanking period is 20 lines/field, the number of effective lines is 525-(20X2)=485. In addition, in LCD preview receivers that use a non-interlace method, the amount of information is twice the number of pixels in the vertical direction,
That is, it corresponds to 220X2=440 dots. Here, if you calculate the overscan rate by J1, it is 220X2/485
=0°907, which means that about 10% overscanning is performed.

Further, since the number of scanning lines in B/G-PAL is 625 and the vertical blanking period is 25 lines/field, the number of effective lines is 625-(25x2)=575. Therefore, in B/G-PAL, it was necessary to configure a liquid crystal television receiver with a different number of pixels from that in M-NTSC. The number of scanning lines is 6 for D/18ECAM as well.
25, and the same can be said.

(Problem to be solved by the invention) As mentioned above, conventionally, B/G-PAL, D/18EC
There was no multi-system liquid crystal television receiver that could support different systems such as AM and M-NTSC.

Therefore, the present invention is intended to eliminate the above problems.
The objective is to realize a multi-system liquid crystal television receiver that can support different television systems by using one liquid crystal panel.

[Structure of the Invention] (Means for Solving Problem S1) The present invention is a liquid crystal television receiver that is capable of receiving signals of various color television systems having different numbers of scanning lines, and which is capable of receiving signals of various color television systems having different numbers of scanning lines. A liquid crystal panel whose number of pixels is set to approximately just scan with a signal of 525 scanning lines, and a vertical driver that sequentially turns on the scanning lines of this liquid crystal panel in synchronization with one horizontal scanning period. , a horizontal driver configured to point-sequentially write pixel data obtained by sampling a video signal onto the signal line of the liquid crystal panel; Generates a control signal for setting each video period in a vertical period and one horizontal period,
a first circuit means capable of switching and setting each video period between a signal with 525 scanning lines and a signal with 625 scanning lines; and a first circuit means for vertically driving the driving means. second circuit means for supplying pulses and horizontal drive pulses, the timing of supply of these drive pulses being controlled by vertical and horizontal control signals from the first circuit means; It is composed of:

Furthermore, as a second invention, in place of the liquid crystal panel of the above invention, the number of pixels in the vertical and horizontal directions is 625, and the number of scanning lines is 625.
From the state of almost just scan in the book signal,
A liquid crystal panel is provided which is set to any state between the states where the number of scanning lines is 525 and the signal is just before the just scan, and the control signal of the first circuit means, the vertical synchronization signal, and the horizontal synchronization are controlled. Based on the signal, when the number of scanning lines is 525, a control signal is generated for controlling the period during which scans are insufficient in the liquid crystal panel to be colored in an arbitrary color, and the control signal is supplied to the drive circuit. 3 circuit means are provided.

(Function) In the present invention, a liquid crystal panel can be scanned almost exactly with an M-NTSC signal having 525 scanning lines, and furthermore, using the same liquid crystal panel, a B/G-NTSC signal having 625 scanning lines can be scanned. Signals such as PAL, D/18ECAM, etc. can also be displayed. Moreover, when the number of scanning lines is 625, the upper side,
The image is overscanned almost evenly at the bottom, allowing the image to be displayed without any unnaturalness.

Furthermore, in the second invention, when displaying a signal with 625 scanning lines, just scan or slightly overscan is performed, and when displaying a signal with 525 scanning lines, the unscanned part is placed on the upper side and the lower side. The colors can be divided into approximately equal parts and colored in any color.

(Example) The present invention will be described below based on the example shown in the drawings.

Before explaining a liquid crystal television receiver according to an embodiment of the present invention with reference to FIG. 1, the number of dots in the horizontal and vertical directions of the liquid crystal panel will be explained with reference to FIG.

In this example, the number of scanning lines is 525.
The SC method almost just scans the vertical direction (
In other words, the number of pixels is set so that there is no overscanning. 240 dots in the vertical direction as shown in Figure 4.

It consists of 480 pixels in the horizontal direction.

To explain this number of pixels, as mentioned above, M−N
In TSC, the number of effective lines is 525-(20X2)=48
There will be 5 pieces. In addition, in LCD television receivers that use a non-interlace method, the number of pixels is half that of an interlace method, so there is no ink lace! ! ! The number of dots in one hundred directions is 485/2-242.5 dots. In reality, it is impossible to set 242.5 dots, so it is set to 240 dots. With this setting, the overscan rate is 240/242.5 = 0.990 units 1°0
It becomes 0. To be exact, it is 1% overscan, but it can be considered as just scan. By setting the number of pixels as described above, it is possible to just scan the M-NTSC vertical direction.

Let's apply a liquid crystal panel with this number of pixels in the vertical direction to a B/G-PAL system with 625 scanning lines. As mentioned above, the number of effective lines in B/G-PAL is 6.
25-(25x2)=575 pieces. The overscan rate in this case is 240x21575-0.835
This results in an overscan of about 16%, and with this level of overscan rate, it is possible to obtain an image without unnaturalness by distributing the image almost equally between the upper and lower sides of the liquid crystal panel.

From the above, by setting the number of pixels as described above, it is possible to simultaneously display signals of each system with 525 and 625 scanning lines.

Regarding the number of dots in the horizontal direction, if there are 480 dots, M-NTSC, B/G-PAL, D/18ECAM
Frequency band (approximately 5MHz
>, therefore, the number of dots may be 480 or more.

FIG. 1 is a block diagram showing the configuration of essential parts of a liquid crystal television receiver according to an embodiment of the present invention.

In this figure, red (R) is output from the video output stage (not shown).
, green (G), blue (B) three primary color signals are X driver 1.2
supplied to The horizontal driver (hereinafter referred to as X driver) 1.2 samples and holds the input signal and converts it into R and G signals.

It is sent to the signal line of the liquid crystal panel 3 as B pixel data. However, the liquid crystal panel 3 has a pixel count of 240 dots in the vertical direction and 480 dots in the horizontal direction. Further, the vertical direction driver (hereinafter referred to as Y driver) 4.5 is 1
The scanning lines are sequentially turned on in synchronization between 11 horizontal scans,
It controls the signals sampled by the X drivers 1 and 2 to horizontally scan them. However, the reason why two systems of X and Y drivers are provided, such as the X driver 1.2 and the Y driver 4.5, is to relieve defects in pixels forming the liquid crystal panel 3. The timing control circuit 6 generates a sampling clock for the X driver 1.2 and a clock for the Y drivers 4 and 5 based on the horizontal and vertical basic clocks supplied as input, thereby adjusting the timing of the liquid crystal display. It is for controlling.

On the other hand, the synchronization separation circuit 7 separates the vertical synchronization signal VD and the horizontal synchronization signal 11D from the composite video signal.
D is input to a vertical counter 9, and the counter 9 generates a control signal VC for setting a video period in one vertical period based on the signal VD. During the setting period of the control signal VC, the vertical oscillation drive circuit 10 generates approximately 240 clocks and supplies them to the timing control circuit 6. On the other hand, the synchronous separation circuit 7 h
The horizontal synchronizing signal HD of s and others is input to the horizontal direction counter 11, and the counter 11 receives a control signal HC for setting the video period in one horizontal period based on the signal HD.
occurs. During the setting period of the control signal HC, the horizontal oscillation drive circuit 12 generates approximately 480 clocks and supplies them to the timing control circuit 6.

The vertical counter 9 and the horizontal counter 11 are provided with switches 9a and 11a, respectively, and by switching these switches, the widths of the control signals VC and HC output from the counters 9 and 11 are changed, and the number of scanning lines is changed. Switching is performed between 525 lines and 625 lines. At the same time, the frequencies of the vertical drive pulse and horizontal drive pulse from circuits 10 and 12 are also switched. The switches 9a and 11a are switched using a 50-meter switch that receives the vertical synchronization signal VD from the synchronization separation circuit 7.
/60H2 This is automatically performed using the discrimination output of the discrimination circuit 8. This means that for the vertical unit 1'rJ signal,
This is because a signal with 525 scanning lines corresponds to 60 Hz, and a signal with 625 scanning lines corresponds to 50' Hz.

Note that the switches 9a and lla may be switched manually without using the discrimination circuit 8.

Next, the operation of the above circuit will be explained with reference to FIGS. 2 and 3.

FIG. 2(a) shows the number of effective lines in one field when performing non-interlaced scanning of a signal such as M-NTSC with 525 scanning lines, and FIG. 2(b) shows the number of effective lines from the vertical counter 9. The timing of the output control signal VC is shown, and FIG. 2(C) shows the vertical drive pulse output from the vertical oscillation drive circuit 10.

That is, in the case of a signal with 525 scanning lines, almost all drive pulses are sent to the timing control circuit 6 by the control signal, so that just scanning is performed.

Figure 3(a) shows B/G-PA L with 625 scanning lines.
3(b) shows the timing of the control signal VC output from the vertical direction counter 9 at this time. (C) shows a vertical drive pulse output from the vertical oscillation drive circuit 10.

In the case of a signal with 625 scanning lines, the drive pulses are distributed approximately equally between the top and bottom of the screen by the control signal, and the blanked drive pulses are distributed in 23 to 24 dots each corresponding to the number of pixels. is sent to the timing control circuit 6.

Above, we have talked about the vertical direction counter 9, but
It is preferable to perform similar signal processing in the horizontal direction as well. That is, for the control signal when the number of scanning lines is 525 and the number of scanning lines is 625 output from the horizontal counter 11, the number of scanning lines is 525 from the vertical counter 9 shown in FIGS. 2 and 3. The width of the control signal in the case of 625 scanning lines is output with a width that is almost the same as the width of the control signal in the case of 625 scanning lines, and the overscan is almost even on the left and right sides. By outputting the vertical direction,
It is possible to perform horizontally balanced switching.

Next, a liquid crystal television receiver according to another embodiment of the present invention will be explained with reference to FIG. 5, but first, with reference to FIG. I will explain about it.

In this embodiment, the number of scanning lines is 625 B/G-
For the PAL system, the number of pixels is set so as to scan almost exactly in the vertical direction. That is, as shown in FIG. 8, the pixel is composed of 280 dots in the vertical direction and 480 dots in the horizontal direction. To explain this number of pixels, as described above, in B/G-PAL, the number of effective lines is 625-(25X2)=575. In addition, in LCD television receivers that use the non-interlace method, the number of pixels is half that of the ink-lace method, and interlace scanning is not performed, so the number of dots in the vertical direction is 57.
5/2=287.5 dots are required. Actually, 287
．． Since setting 5 dots is impossible, it is set to 280 dots.

With this setting, the overscan rate is 280/
287.5-〇, 975#1. It becomes O. To be exact, 2.
Although it is a 5% overscan, it can be considered a just scan. By setting the number of pixels as described above, it is possible to just scan the B/G-PAL vertical direction.

Let's apply a liquid crystal panel with this number of pixels in the vertical direction to an M-NTSC system with 525 scanning lines. As mentioned above, the number of effective lines in M-NTSC is 525.
- (20x2) = 485 pieces. For LCD television receivers that use a non-interlaced system,
Since only 1/2 the number of pixels is required, 485/2 = 242.5 dots, or 242 to 243 pixels, is sufficient, which is the same as B described above.
When applied to a liquid crystal panel (see Figure 9) that performs almost just scan with the /G-PAL signal, 242-280=-3
There will be 8 dots, and an extra portion of the liquid crystal panel will appear where no signal will be displayed. This extra part would look unnatural if displayed on the screen as it is, so the extra liquid crystal panel part is approximately equal on the upper and lower sides.

A preferable display can be achieved by distributing the information to the area and displaying this area in an arbitrary color.

Regarding the number of dots in the horizontal direction, if there are 480 dots, M-NTSC, B/G-PAL, D/18ECAM
Frequency band (approximately 5MHz
), therefore, the number of dots may be 480 or more.

FIG. 5 shows a liquid crystal television receiver B1 according to another embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of main parts of the machine.

In this figure, the R, G, and B signals are connected to the X driver 21.2.
2 is sampled and held and supplied to the liquid crystal panel 23 signal line. The liquid crystal panel 23 is vertically oriented 28
The number of pixels is 0 dot and 480 dots in the horizontal direction. A signal is supplied from the Y drivers 24 and 25 to the scanning lines of the liquid crystal panel 23 to sequentially turn on each scanning line in synchronization with one horizontal scanning period. The timing control circuit 26 includes a vertical oscillation drive circuit 30. The Y driver 24.2 uses the vertical drive signal and horizontal drive signal from the horizontal direction oscillation drive circuit 32 as a reference clock.
5 and sampling clocks to the X drivers 21 and 22 to control the timing of the liquid crystal display. On the other hand, the synchronization separation circuit 27 converts the composite video signal into vertical one.
! The vertical synchronizing signal VD is input to a vertical counter 29, and the counter 29 generates a control signal VC for setting a video period in one vertical period. During the setting period of the control signal VC, the I true direction oscillation drive circuit 30 generates approximately 280 clocks and supplies them to the timing control circuit 26. Further, the vertical direction counter 29 creates a control signal for the coloring drive circuit 33 based on the vertical synchronization signal VD and the setting 1g1 of the control signal VC. In response to this control signal, the coloring drive circuit 33 uses a control signal ICI to color the extra portion on the screen in an arbitrary color when the number of scanning lines is 525.
is generated and supplied to the X drivers 21 and 22.

On the other hand, the horizontal synchronization signal HD from the synchronization separation circuit 27 is input to the horizontal direction counter 31, and the counter 31 receives the signal H.
A control signal HC for setting a video period in one horizontal period is generated based on D. During the setting period of the control signal HC, the horizontal oscillation drive circuit 32 generates approximately 480 clocks and supplies them to the timing til+ control circuit 26. Further, the horizontal counter 31 generates a control signal for the coloring drive circuit 33 based on the horizontal synchronizing signal HD and the set period of the control signal HC. In response to this control signal, the coloring drive circuit 33 generates a control signal IC2 for coloring the extra portion on the screen in an arbitrary color when the number of scanning lines is 525, and supplies it to the Y drivers 24 and 25.

The vertical direction counter 29 and the horizontal direction counter 31 are respectively provided with switches 29a and 31a,
By switching these switches, the on/off timing of the counter 29.31 output is changed, and the number of scanning lines is 52.
The width of the control signals VC and HC is switched between 5 lines and 625 lines. At the same time, the frequencies of the vertical drive pulse and horizontal drive pulse from circuits 30 and 32 are also switched. Switching of the switches 29a and 31a is automatically performed by the discrimination output of a 50/60Hz discrimination circuit 28 which receives the vertical synchronization signal VD from the synchronization separation circuit 27 as input.

This means that for the vertical synchronization signal, the number of scanning lines is 525.
This is because one signal corresponds to 60H7, and 625 signals corresponds to 50H2. Note that the switches 29a and 31a may be switched manually without using the discrimination circuit 28.

Next, the operation of the above circuit will be explained with reference to FIGS. 6 and 7.

Figure 6(a) shows the number of effective lines in one field when performing non-interlaced scanning of a signal such as B/G-PAL with 625 scanning lines, and Figure 6(b) shows the number of effective lines in one field. 6C shows the timing of the control signal VC output from the vertical oscillation drive circuit 30. FIG.

That is, in the case of a signal with 625 scanning lines, almost all the vertical drive pulses are sent to the timing control circuit 26 by the control signal VC, so that the upper and lower sides of the screen are just scanned. .

Figure 7 (a) shows the number of effective lines in one field when performing non-interlaced scanning of a signal such as M-SC with 525 scanning lines, and Figure 7 (b) shows the number of effective lines in one field. The timing of the control signal VC outputted from the vertical direction counter 29 is shown, and FIG. 7(C) shows the vertical drive pulse outputted from the vertical direction oscillation drive circuit 30.

If the signal has 525 scanning lines, use the control signal @VC.
As a result, the vertical drive pulses are distributed almost equally to the upper and lower parts of the screen where there is no signal, and the vertical drive pulses distributed in 19 dots each corresponding to the number of pixels are distributed to the timing control circuit 26. It is designed to be sent to.

Although the vertical direction counter 29 has been described above, it is preferable to perform similar signal processing in the horizontal direction as well. That is, the control signals output from the horizontal counter 31 when the number of scans i is 525 and the number of scan lines is 625 are shown in FIGS. 6 and 7! The width of the control signal from the direct direction counter 29 is approximately the same as the width of the control signal when the number of scanning lines is 525 and the width of the control signal when the number of scanning lines is 625. Alternatively, the overskin 11 can perform well-balanced switching in the vertical and horizontal directions by not outputting an output that would result in insufficient scanning width or overscanning that is nearly uniform on the left and right sides.

Next, the display relationship between a signal with 525 scanning lines and a signal with 625 scanning lines, including the above embodiment, will be described with reference to FIG.

FIGS. 9(a) to 9(C) illustrate just scan, overscan, and insufficient scan, with the dashed line range being the just scan range above and below the display screen.

(a) is a signal with 525 scanning lines (for example, M-NTSC
), an overscan of about 16% occurs in a signal with 625 scanning lines. (C) is a signal with 625 scanning lines (for example, B
/G-PAL) and a signal with 525 scanning lines results in a scanning shortage of approximately 15%. Therefore, between the state shown in (b) where the signal with 525 scanning lines is set a little before just scanning (insufficient scanning), and the state shown in (C) where the signal with 625 scanning lines is just scanned. By selecting an arbitrary state and coloring the insufficiently scanned portions in an arbitrary color when displaying a signal such as the M-NTSC system with 525 scanning lines, the insufficiently scanned portions will also be reduced, and the It is possible to create a state in which the number of parts is reduced, and a better display can be achieved. To set such a state, the number of pixels in the vertical and horizontal directions of the liquid crystal panel 23 shown in FIG. 5 must be set, and the vertical counter 29. By changing the set value of the horizontal direction counter 31, the insufficient scanning area and the overscanning area 2 can be changed.

[Effects of the Invention] As described above, according to the present invention, there is provided a multi-type liquid crystal television that can satisfactorily display signals with the number of scanning lines of 525 and 625 using one liquid crystal panel. A receiver can be realized.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the liquid crystal television receiver of the present invention, Figs. 2 and 3 are explanatory diagrams explaining the operation of Fig. 1, and Fig. 4 is the liquid crystal panel of Fig. 1. FIG. 5 is a block diagram showing another embodiment of the present invention. FIGS. 6 and 7 are explanatory diagrams explaining the operation of FIG. 5. The figure is a block diagram showing the number of pixels in the vertical and horizontal directions of the liquid crystal panel in Figure 5. Figure 9 is an explanatory diagram explaining the display relationship between the signal with 525 scanning lines and the signal with 625 scanning lines. FIG. 10 is an explanatory diagram showing the number of pixels in the vertical and horizontal directions of a liquid crystal panel used in a conventional liquid crystal television receiver. 1.2, 21.22...X driver, 3.23...
LCD panel, 4.5.24.25...Y driver, 6.26...
Timing control circuit, 7.27... Synchronization separation circuit, 8.28... 50/60H2 discrimination circuit, 9.29...
・Vertical direction counter, 10.30... Vertical direction oscillation drive circuit, 11.3
1...Horizontal counter, 12.32...Horizontal oscillation drive circuit, 33...
・Coloring drive circuit. Figure 2 Figure 6 Figure 4 Figure 8 Figure 10

Claims (2)

[Claims] (1) A liquid crystal television receiver that is capable of receiving signals of various color television systems with different numbers of scanning lines, and which has approximately the same number of pixels in the vertical and horizontal directions for a signal with 525 scanning lines. A liquid crystal panel set to scan, a vertical driver that sequentially turns on the scanning lines of this liquid crystal panel in synchronization with one horizontal scanning period, and pixels that sample video signals for the signal lines of the liquid crystal panel. A driving means comprising a horizontal driver that writes data dot-sequentially, and control for setting each video period in one vertical period and one horizontal period based on a vertical synchronization signal and a horizontal synchronization signal of the video signal. Something that generates a signal,
a first circuit means capable of switching and setting each video period between a signal with 525 scanning lines and a signal with 625 scanning lines; and a first circuit means for vertically driving the driving means. a second circuit means for supplying pulses and horizontal drive pulses, the supply periods of the drive pulses being controlled by vertical and horizontal control signals from the first circuit means; A liquid crystal television receiver characterized by comprising the following. (2) A liquid crystal television receiver that is capable of receiving signals of various color television systems with different numbers of scanning lines, in which the number of pixels in the vertical and horizontal directions is approximately just the same for a signal with a number of scanning lines of 625. The liquid crystal panel is set to any state between the scan state and the state before just scan when the number of scanning lines is 525 signals, and the scanning lines of this liquid crystal panel are synchronized to one horizontal scanning period. and a horizontal driver that sequentially writes pixel data obtained by sampling a video signal onto the signal line of the liquid crystal panel in a dot-sequential manner. Generates a control signal for setting each video period in one vertical period and one horizontal period based on a periodic signal and a horizontal synchronization signal,
a first circuit means capable of switching and setting each video period between a signal with 525 scanning lines and a signal with 625 scanning lines; and a first circuit means for vertically driving the driving means. a second circuit means for supplying pulses and horizontal drive pulses, the supply periods of these drive pulses being controlled by vertical and horizontal control signals from the first circuit means; , a control signal of the first circuit means and the vertical synchronization signal;
Based on the horizontal synchronization signal, a control signal is generated to control the period during which scans are insufficient in the liquid crystal panel to be colored in an arbitrary color when the number of scanning lines is 525, and is supplied to the drive circuit. A liquid crystal television receiver characterized by comprising: third circuit means for performing the following steps.